Fish preference by the harbour seal (Phoca vitulina), with implications for the control of damage to fishing gear

This study compares food preference for different fish species by harbour s eals in a seal colony off the northwest coast of Sweden. Seals were offered several different species of dead fish in net cages and showed a preferenc e for herring, gadids and flatfish. Other fish such as eel and eelpout were mostly rejected. Five-bearded rockling, bullrout and small labrids were al ways rejected. Seal visits occurred at only 30% of the total number of feed ing opportunities, in spite of the fact that seals were constantly present in the area. The temporal and spatial aggregation of the pattern of seal vi sits to the cages was not randomly distributed. This study suggests that on ly a minority of the seals in the area used the baited cages and that the f eeding preferences could be a result of specialised prey selection. This ha s important implications for the choice of appropriate management options t o control seal damage of fishing gear. It is predicted that it may be a mor e successful and efficient option to focus on those individual seals found in the vicinity of the fishing gear, rather than to carry out random cullin g amongst the whole population. (C) 2001 International Council for the Expl oration of the Sea.